Technical aspects of the magnetic transcutaneous coupling of EMG signals

For long time application of myoelectric signal read-out (e.g, for patients with controllable limb prothesis), a method, which avoids either the disadvantages of skin surface electrodes or the percutaneous galvanic conductors, is described. The myoelectric energy is inductively coupled out through the skin without amplification or any implanted energy source (or energy coupled or radiated into the body from an extracorporeal source). The electrodes are placed directly at or inside the muscle which generates the wanted signals and are connected by means of two ductile wires to the coil fixed subcutaneously. Achieved advantages are: good separation of signals originating from different muscles, improvement in the delivery of signals for a proportional control (to muscle activity) of, e.g., artificial limbs, and high probability of a good long time reliability because of the technical simplicity.